You must create a `RailsCasts` theme inside IntelliJ first. Do this in Settings > Editor > Colors & Fonts, select any existing scheme and click "Save As" and name the new scheme `RailsCasts` Close IntelliJ, then go to `~/Library/Preferences/IntelliJIdea12/colors` and there should be a `RailsCasts.icls` file which can be replaced with this one.